Task 1
1 describe the elements of communication systems
2 explain the characteristics of electromagnetic waves and their application to communications systems
3 determine the signal spectra for the content of complex waveforms
4 convert from linear to logarithmic relationships (and vice versa) and determine the overall gain/loss of typical communication systems
Q1
A radio signal is to be transmitted and received
(a) Draw a block diagram of a communication channel
(b) Describe the basic function of each block
Q2
Discuss the general categories by which electromagnetic waves are characterised, explaining the terms used and show how these are positioned in the electromagnetic spectrum
Q3
Using your knowledge of waveform spectra gained in UNIT 2 (Engineering Science) determine the signal spectra for the waveform shown below. Illustrate your answer by plotting each of the waveforms separately together with the the combined waveform. In addition show your results plotted in the frequency domain.
Q4
(a) Various stages of a receiver circuit are illustrated below and the voltage levels at the end of each stage are shown.
Calculate: (a) power gain or loss at each stage
(b) overall power gain
(c) power into the detector if the power into the first stage from the antenna is 2pW
(b)Three amplifiers in a communication system are connected in series by cables. The cable lengths are:
Cable1 0.1m
Cable2 0.4m
Cable3 2.0m
Calculate Pout if Pin is -5dB and the insertion loss for the line is 1 dB per metre.
Task 2
1 determine the sources and effect of noise found in electronic communication systems, including cumulative factors
2: carry out noise calculations
Q5
(a) Identify the sources of noise in the RF amplifier below.
(i) Explain why it is a source of noise
(ii) Identify the type of noise
(b) Which factors are used to quantify the cumulative effect of noise?
Q6
(a) An amplifier has a noise figure of 13dB. Calculate the equivalent amplifier input noise power for a bandwidth of 1MHz.
(b) A mixer stage has a noise figure of 20db and this is preceded by an amplifier with a power gain of 15dB and a noise figure of 9dB. Calculate the overall noise figure referred to the input.